1 tablespoon chopped fresh sage leaves (about 4 large leaves), plus additional for topping
Lightly coat the bottom of a 5- or 6-quart slow cooker with cooking spray. In a large saucepan, warm the oil over medium-low heat. Add the shallots, salt, and pepper. Sauté until the shallot is soft and translucent but not brown, about 10 minutes. Add the wine and cook for 2 minutes.
Transfer the shallot mixture to the slow cooker. Add the squash, 3 1/2 cups broth, and rice. Cook on high for 2 1/2 to 3 hours (or on low for 4 to 6 hours), until the rice is tender and creamy. Check the broth level towards the end of the cooking time to ensure the risotto doesn’t dry out. If it seems too dry, stir in a bit more broth as needed.